1. Field of the Invention
The present invention relates to transparent-oxide-film compositions with high conductivity and, more particularly, to transparent conductive cadmium tin oxide films with properties of high transmittance and low specific electrical resistance.
2. Description of Related Art
Science and technology continues to progress rapidly and increasingly permeates the real, daily lives of people rather than general unseen improvements. In terms of electronic devices, consumers nowadays not only search for products with smaller sizes, but also demand humanized and easy-to-use features within them. Integration of those communication products such as Personal Digital Assistants (PDA), Liquid Crystal Displays (LCD) and 3C products in recent years is designed to cater to such demand.
Manufacturing the above-mentioned products requires a large amount of transparent electrode, among which the most commonly used material is indium tin oxide (In2O3:Sn). Also known as ITO, it is the product obtained after mixing indium oxide with a small amount of tin. However, the demand for a better conductivity and transmittance from the transparent conductive film increases as the high definition and high response speed of flat panel displays, such as OLED, develop over time. Besides, while the manufacturing rates of flat panel displays, LED lights and various kinds of applications involving indium increase nowadays, the demand for this rare metal is expected to go nowhere but upward. It is only a matter of time before indium will be consumed to it s depletion. Hence, a solution must be provided as soon as possible as a precaution. Based on the two factors as mentioned above, it is essential to develop a non-indium transparent conductive film with better conductivity while possessing great transmittance property at the same time.
In a cation having a configuration of (n−1)d10ns0(n≧4), In+3 or Cd+2 has a broad orbital. Given a proper introduction of carriers, high-quality conductivity can be carried out. Therefore, it is applicable to dope a proper amount of tin into cadmium oxide to substitute for indium tin oxide (ITO). The purpose of doping tin into cadmium oxide is to replace cadmium in the oxide structure, forming an n-type TCO material. Due to very high transmittance in the visible light band (light wavelength between 400 nm and 700 nm) and great conductivity, the transparent conductive film of cadmium tin oxide (CdO—SnO2) possesses both low resistivity and high transmittance properties at the same time.